1) (1-7/10)*х=2 1/4
(10/10-7/10)*х=2 1/4
3/10*х=2 1/4
х=2 1/4:3/10 2 1/4:3/10=9/4*10/3=30/4=7 2/4=7 1/2
x=7 1/2
2) (3 1/8+1 3/4)*x=2 1/6
(3 1/8+1 6/8)*x=2 1/6
4 7/8*x=2 1/6
x=2 1/6:4 7/8 2 1/6:4 7/8=13/6:39/8=13/6*8/39=4/9
x=4/9
3) (1/4+1/5)*x=1 4/5
(5/20+4/20)*x=1 4/5
9/20*x=1 4/5
x=1 4/5:9/20 1 4/5:9/20=9/5*20/9=4
x=4
4) (2 1/12-1 5/6)*x=3/4
(1 13/12-1 10/12)*x=3/4
3/12*x=3/4
1/4*x=3/4
x=3/4:1/4 3/4:1/4=3/4*4/1=3
x=3